title: Endothelial adhesion receptors are recruited to adherent leukocytes by inclusion in preformed tetraspanin nanoplatforms.
abstract: VCAM-1 and ICAM-1, receptors for leukocyte integrins, are recruited to cell-cell contact sites on the apical membrane of activated endothelial cells. In this study, we show that this recruitment is independent of ligand engagement, actin cytoskeleton anchorage, and heterodimer formation. Instead, VCAM-1 and ICAM-1 are recruited by inclusion within specialized preformed tetraspanin-enriched microdomains, which act as endothelial adhesive platforms (EAPs). Using advanced analytical fluorescence techniques, we have characterized the diffusion properties at the single-molecule level, nanoscale organization, and specific intradomain molecular interactions of EAPs in living primary endothelial cells. This study provides compelling evidence for the existence of EAPs as physical entities at the plasma membrane, distinct from lipid rafts. Scanning electron microscopy of immunogold-labeled samples treated with a specific tetraspanin-blocking peptide identify nanoclustering of VCAM-1 and ICAM-1 within EAPs as a novel mechanism for supramolecular organization that regulates the leukocyte integrin-binding capacity of both endothelial receptors during extravasation.
authors.affiliation: Servicio de Inmunología, Hospital de la Princesa, Universidad Autónoma de Madrid, 28006 Madrid, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Barreiro
authors.forename: Moreno
authors.initials: M
authors.lastname: Zamai
authors.forename: María
authors.initials: M
authors.lastname: Yáñez-Mó
authors.forename: Emilio
authors.initials: E
authors.lastname: Tejera
authors.forename: Pedro
authors.initials: P
authors.lastname: López-Romero
authors.forename: Peter N
authors.initials: PN
authors.lastname: Monk
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Valeria R
authors.initials: VR
authors.lastname: Caiolfa
authors.forename: Francisco
authors.initials: F
authors.lastname: Sánchez-Madrid
mesh_terms: D015703:Antigens, CD / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D016023:Integrins / Q000235:genetics / Q000502:physiology; D018799:Intercellular Adhesion Molecule-1 / Q000502:physiology; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D011956:Receptors, Cell Surface / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014471:Umbilical Veins / Q000502:physiology / Q000648:ultrastructure; D019010:Vascular Cell Adhesion Molecule-1 / Q000502:physiology
chemical_list: D015703:Antigens, CD; D016023:Integrins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1